Automatic electrode clamping device



May 13, 1958 J. A. vANNosTRAN 2,834,824

AUTOMATIC ELECTRODE CLAMPING DEVICE Filedy May 27. 1957 4 Sheets-Sheet l'full'.

May 13,' 1958 J. A. VAN NosTRAN 2,834,824

AUTOMATIC ELECTRODE CLAMPING DEVICE 4 She'ets-Sheet 2 Filed hay 27, 1957l2 L4 l l I lIl'J I I I3 I r INVENTOR.

Juelz 14.VanN0s m1z BY JMJ o Fig. 4 4

v ATTORNEYS May 13, 1958 J. A. VAN NosTRAN 2,834,824

AUTOMATIC ELECTRODE CLAMPING DEVICE Filed May 27,' 1957 4 Sheets-Sheet 3INVENTOR.

64 Jaz/01rd. VznNasfrem AATTaRNElS May 13, 1958 J. A. VAN Nos'rRAN Y2,834,824

AUTOMATIC ELE'cTaoDE CLAMPING DEVICE Filed May 27, 1957l INVENTOR.

Jac/Iz Walz/Nash@ BY gwf ATTREKS' 4 Sheets-Sheet 4 Unitd rates arent Oassista AUTOMATIC Erncrnonn orar/irme nnvrcs Jack A. Van Nostran,Canton, Ghia, assigner to hio Ferro-Alloys Corporation, Canton, Ghia, acorpora tion of Ohio Application May 27, 1957, Serial No. 651,710

l2 Claims. (Cl. )t3- 16) The invention relates to improvements inholders for electrodes in electric arc furnaces, and more particularlyto a spring-operated clamp for holding an electrode and uid pressuremechanism for releasing the clamp.

ln such electrode holders as are now in general use, the pressurecompensating mechanism for the electrode clamp tends to become very hotduring operation, due to the proximity thereof to the extremely hotelectrode. As spring means is ordinarily used in such mechanism, the eX-treme heat to which the spring is thus subjected causes rapiddeterioration of the spring. Attempts have been made to cool suchmechanism, but such devices as have been used have relativelycomplicated cooling arrangements.

Itis therefore an object of the present invention to provide aspring-operated electrode clamp in which the spring mechanism is locatedat a point remote from the hot electrode.

Another object is to provide such a device in which the spring mechanismis located remote from the clamping members and operatively connectedthereto by levers.

A further object is to provide a device of this character in which theclamping members are forced against the electrode by a spring undercompression, the spring being contained within and water cooled withinan enclosure.

A still further object is to provide a device of this type in which thespring is contained within a watercooled enclosure together with ahydraulic cylinder which may be operated to overcome the springpressure.

Another object of the invention is to provide such electrode clampingmeans in which there is a continuous circuit of water cooling theinterior of the cylinder, the Water circuit being controlled so as tobecome a trapped system upon which high pressure can be applied tooperate the cylinder.

A further 4object is to provide a clamping means of this character inwhich a compressible fluid may be provided in the cylinder instead of acompression spring for forcing the clamping members against theelectrode.

A still further object is to provide an electrode clamp of the typereferred to in which the cylinder is operatively connected to theclamping members by a pair of watercooled levers which may be eithercollaterally pivoted or decussately pivoted, as may be adapted tovariations in design of the spring-hydraulic cylinder.

It is also an object of the invention to provide such clamping means inwhich a duplex cylinder or fluid pressure accumulator is provided forapplying high pressure to the water trapped in the circuit supplying thespringloaded cylinder.

Another object is to provide electrode clamping means of the characterreferred to having a spring-hydraulic cylinder with a piston therein andmeans for continuously circulating cooling water within the cylinder oneach side of the piston.

A further object is to provide electrode clamping means of this type inwhich a compressible fluid is located Within the cylinder on one side ofthe piston and adapted to be compressed by uid pressure on the -otherside of the piston, and in which cooling Water is circulated through acoil within the compressible fluid.

And finally, it is an object of the present invention to provide such adevice in which cooling water may be continuously circulated within thecylinder on each side of the piston, and high pressure may be applied tothe cooling water on one side of the piston for operating the cylinderto release the clamping members.

The above and other objects, apparent from the drawings and followingdescription, may be attained, the above described difficulties overcomeand the advantages and results obtained, by the apparatus, construction,arrangement and combinations, subcombinations and parts which comprisethe present invention, a preferred embodiment of which, illustrative ofthe best mode in which applicant has contemplated applying theprinciple, being set forth in detail in the following description andillustrated in the accompanying drawings.

in general terms, the invention may be brielly described as comprisingan automatic electrode clamping device comprising clamping members inthe form of a pair of substantially semi-circular clamping bandshingedly connected together at one end, and encircling an electrode.These clamping bands may be water cooled as in usual practice.

The clamping bands are forced against the electrode by means of anoperating cylinder having a piston therein, and operatively connected tothe clamping bands through a pair of pivoted, water-cooled leversconnected at opposite ends to the cylinder and to the free ends of theclamping bands. These levers may be either collaterally pivoted ordecussately pivoted, depending upon the design of the cylinder.

Pressure is applied to one side of the piston to normally force theclamping bands into clamping engagement with the electrode. Thispressure may be produced by a compression spring located within thecylinder, upon one side of the piston, or by a compressible fluidlocated in the cylinder on that side of the piston.

The cylinder is cooled by means of a continuous circuit of cooling wateron each side of the piston. The circuit of cooling water, on theopposite side of the piston to the pressure means, is so controlled asto become a trapped system so as to apply pressure upon that side of thepiston to overcome the spring or compressible fluid in order to releasethe clamping bands.

A duplex cylinder or fluid pressure accumulator is provided for applyinghigh pressure to the water trapped in the circuit supplying thespring-loaded cylinder.

Having thus brielly described the invention, reference is now made tothe accompanying drawings showing preferred embodiments of theinvention, in which:

Fig. l is a front elevation of an embodiment of the improved electrodeclamping device, showing a springloaded cylinder operatively connected7through collaterally pivoted water-cooled levers, to the electrodeclamping bands, parts being broken in section for the purpose ofillustration;

Fig. 2 is a side elevation of the electrode clamping device shown inFig. l;

Fig. 3 is a horizontal sectional view taken on the line 3 3, Fig. l.,showing an electrode clamped within the clamping bands;

Fig. 4 is a fragmentary side elevation showing the electrode clampedwithin the clamping bands;

Fig. 5 is a longitudinal sectional view through the duplex cylinder oriluid pressure accumulator for applying high pressure to the watertrapped in the circuit supplying the spring-loaded cylinder;

Fig. 6 is a diagrammatic view showing the valves and piping connectingthe spring-loaded cylinder, the `circuit supplying water thereto, theduplex cylinder and the high pressure fluid system;

Fig. 7 is a longitudinal sectional View through a moditied form ofcylinder, in which a compressible fluid is substituted for the springpressure on one side of the piston; and

Fig. 8 is a 'front elevation with parts broken away of a modifiedembodiment of the invention in which a modified spring-loaded .cylinderis shown operatively connected to the clamping bands through a pair ofdecussately pivoted levers.

Referring now more particularly to the embodiment of the inventionillustrated in Figs. 1 to 6, a portion of an electrode is indicated at1t). The electrode clamping members comprise a pair of substantiallysemi-circular clamping 'bands 11, hingedly connected together at oneend, `as indicated at 12, and having conventional pads 13 on their inner:sides for contact with the electrode, as best shown in Fig. 3.

Each `of the clamping bands 11 is water cooled. For this purpose,passages 14 are provided through each clamping band and nipples 15 areprovided thereon for the attachment of hose or the like for continuouslycirculating cooling water through the passages 14.

A socket 16 is formed in the free end ot each of the clamping bands 11for receiving pressure means for forcing the two bands toward each otherso `as to clamp the electrode therebetween.

As shown in Figs. 1 to 4, this pressure means includes a pair of levers,indicated generally at 17. These levers have ybosses 18 on their lowerends located in the sockets 16 of the clamping `bands `and adapted to benormally urged toward each other by means of a spring-loaded cylinderindicated generally at 19 and operatively connected to the upper ends ofthe levers i7.

Each of the levers 17 is adapted to be water cooled and for this purposeeach lever comprises a spaced pair of hollow legs 20 communicating attheir lower ends as at 20a whereby cooling water may be circulatedentirely therethrough.

The levers 17 are lcollaterally pivoted by means of a hollowwater-cooled bolt 21, one end ot' which is pivotally connected to oneleg Ztl as at 22. The other end of the bolt 21 is located `between thespaced legs 20 of the other lever 17 and is located through a plate 23bearing against or attached to the outer side of said other lever 17.

A 'nut 24, with rounded surface 25 bearing upon the plate 23, isthreaded upon the end of the bolt 21, thus permit-ting pivotal movementof the two levers 17 relative to the water-cooled bolt 21.

Cooling water may be circulated through the hollow levers 17 and hollowlbolt 21 by means of a hose or the like attached to the inlet 26 in onehollow leg 2i) of one lever 17. f

An 'outlet nipple 27 communicates with the other hollow leg 2t) of thislever 17 and is connected to a hose or tubing 28 as by the iitting 29.The tubing 2S is connected, yby inlet fitting 30, to the hollow bolt 21,and an outlet litting 31 upon said hollow 1bolt is connected by a hoseor tubing 32 to a iitting 33 attached to the inlet nipple 34 in onehollow leg 2t) of the other lever 17.

An outlet nipple 35 on the other hollow leg 20 of said last-named lever17 is connected by tting 36 with a hose or tubing 37. Thus, water may becontinuously circulated through both legs of each lever 17 and throughthe hollow holt 21.

The cylinder, indicated generally at 19, is provided with the heads 33and 39 at opposite ends thereof. The head 33 has an ear 40 integrallyformed thereon, or rigidly attached thereto, and pivotally connected tothe upper end of the adjacent lever 17 `as by the pivot pin 41.

A piston 42 is `slidably mounted within the cylinder 19 and the pistonrod 43 thereof is located through the stuing box 44 in the head 39 ofthe cylinder and provided at 'its outer end with an eye 45 pivotallyconnected to the other lever 17, as by the pivot pin 46.

The piston 42 is normally urged toward the right, as viewed in Fig. l,by means of a coil spring 47 located within the cylinder 19 undercompression between the head 38 and the piston 42. A rod 48 may bemounted upon the piston for Contact with the head 38 of the cylinder toact as a stop for the piston in order to limit the` compression of thespring 47 The cylinder 19 is adapted to be continuously water cooled.For this purpose, an inlet 49 is provided in the head 38 and connectedby titting 50 with the tube 37. The inlet communicates through alongitudinal passage 51 with the inlet pipe 52 extending longitudinallywithin the cylinder and located within the coil spring 47.

A longitudinal outlet passage 53 provides communication between theinterior of the cylinder and the outlet port 54 to which an outlet pipeor hose 55 may be connected. For the purpose of continuously watercooling the other end of the cylinder 19, upon the opposite side of thepiston 42, an inlet passage 56 is formed in the head 39 and communicateswith the water supply pipe 57.

An outlet passage 58, in the head 39, communicates with the outlet pipe59. Thus, cooling water may be continuously circulated, by separatecircuits, through each end of the cylinder, on opposite sides of thepiston.

Although the cooling water continuously circulates through the inlet 49and outlet 55, continuously cooling the coil spring 47 and adjacentportion of the cylinder 19, means is provided for controlling thecirculation of water through the other end of the cylinder, that isthrough the inlet pipe 57 and outlet pipe 59.

This means is shown in Fig. 6 as a valve indicated generally at 60. Thisvalve is shown of the rotatable plug type, the rotatable plug 61 havinga port 62 therethrough which, as shown in full lines in Fig. 6, normallyconnects the pipe 59 with the outlet pipe 63, so that water from thesupply pipe 57 continuously flows freely through this end of thecylinder, with the valve in this open position.

When the valve plug 61 is turned to the closed position, an'indicated bybroken lines in Fig. 6, it will be seen that this circuit will become atrapped system, since the check valve 64 will prevent the Water frompassing backward in the supply pipe 57.

Thus, pressure in this end of the cylinder Will tend to move the pistonagainst the pressure of the spring 47, operating the levers 17 torelease the clamping bands 11 Iand permit the electrode 1i) to slidedownward in the furnace.

For Ithe purpose of applying high pressure to the water trapped in thiscircuit, a duplex cylinder or uid pressure accumulator indicated`generally at 65 in Figs. 5 and 6, is provided in association with asecond water supply lino 66 and an oil supply line 67.

A duplex piston, comprising a spaced pair of pistons l68 and 68a joinedby a rod 68h, is located within the Cylinder 65. Heads 69 and 70 arelocated in opposite ends of the cylinder 65. An outlet 65a in the centerof the duplex cylinder 65 provides for the discharge to the atmosphereof any leakage of water or oil which may pass around the pistons 68 and68a respectively to the center of the cylinder. The head 69 has an inletpassage 71 therein connected by pipe 72 with the por-t 81 of the valve73 in lthe oil line 67.

The head 7() has an inlet passage 74, communicating with the watersupply pipe 66, and an outlet passage 75 communicating with the pipe 76leading to the -port 77 in 'the valve 7S.

Normally the rotary plug 79 of the oil valve 73 is located in the fullline position shown in Fig. 6, so that the passage 8i) therein formscommunication between the port 81 communicating with the pipe 72 and'the port 82 communicating with 'the oil return pipe 83.

The inlet port S4 of this valve is thus closed, so .that oil pressurefrom the oil sup-ply pipe 67 cannot pass through the valve 73 to theduplex cylinder 65.

rThe rotary valve plug 85 of the valve 78 is normally in the full line,position shown in Fig. 6, so that the passage 86 therethrough does notprovide communication between the water inlet pipe '76 and the wateroutlet pipe 87.

The valves 60, 78 and 75 z re all adapted to be operated simultaneously,by means or' the levers 88 connected to the valve plugs, and the link09, so that the three valves may be moved in unison from the full lineposition to the broken line position shown in Fig. 6.

When the valves are moved to this broken line position, the valve plug61 of the valve 60 will be closed, preventing discharge of water fromthe cylinder 19 through the pipe 59. At the same time the valve '78 willbe opened, permitting iiow or" water from the supply pipe 66 through theinlet 74 and outlet 75 of the duplex cylinder 65, then through the pipe76, valve 7S and pipes 87 and 57 to the spring-loaded cylinder 19.

At the same time, oil under pressure will be admitted from oil supplyline 67 through the valve 73 and inlet 71 to the other end of the duplexcylinder 65, against the piston 68a, forcing the same to the right, asViewed in the drawings, and as the piston 68 is thereby moved to theright, high pressure will be built up in the water line 76, S7 and 57 tothe spring-loaded cylinder 19, thus immediately overcoming the presssureof the spring 47 therein and operating the levers 17 to release theclamping bands 11.

The above-described device may be modiiied by substituting for thespring-loaded cylinder 19 a cylinder in which the piston is pressureloaded with a compressible liuid instead of a spring. Such a cylinder isindicated generally at 19a in Fig. 7. The piston 42a is slidably locatedWithin the cylinder and is provided with a rod 43a having an eye 45a atits end for pivotal connection to one of the levers in the manner abovedescribed and as illustrated in Fig. l.

The piston rod 65a is slidable through a stuing boX 44a in the head 39aof the cylinder. An inlet passage 56a in the head 39a communicates withthe water supply pipe 57 and an outlet passage 58a in the head 39acommunicates with the water outlet pipe 59.

Thus water may be admitted from the pipe 57 to the interior of thecylinder 19a on the right side of the piston 42a as viewed in Fig. 7,and discharged through the outlet passage 55a to the pipe 59 in the samemanner as illustrated and described with reference to Figs. l and 6.

The pipe 59 would of course lead to the valve 60 as shown in Fig. 6 sothat the circuit of cooling water passing through this side of thecylinder may be trapped in order to move the piston to the left.

For the purpose of limiting movement of the piston toward the left, asviewed in Fig. 7, a stop ring 90 is Welded or otherwise secured withinthe cylinder 19a at the desired point.

Instead of providing a compression spring within the cylinder 19a tonormally urge the piston 42a to the right, in the manner illustrated anddescribed with reference to Fig. 1, the cylinder is lled with acompressible fluid between the piston 42a and the head 38a for normallyurging the piston 42a to the right, as shown in Fig. 7.

An integral rod 40a is attached to the head 38a of the cylinder andprovided with an eye for pivotal attachment to the other lever in themanner above described and as illustrated in Fig. 1.

For the purpose of water cooling the interior of the cylinder 19a, onthe left side of the piston 42a, as viewed in Fig. 7, a water coolingcoil 91 is shown connected at one end to the cooling water inlet 49a inthe head 38a and at the other end to the cooling water discharge port54a in the head 38a of the cylinder.

With this construction the clamping device may be operated in the mannerabove described with reference to Fig. l. Normally, the compressiblefluid within the cylinder upon the left side of the piston will urge thepiston toward the right in order to operate the levers to 6 hold theclamping device in clamping position around the electrode.

When the valve 60 in Fig. 6 is closed to trap the cooling water in thepipe 59, the water pressure on the right side of the piston 42a willbecome suicient to compress the compressible fluid on the left side ofthe piston so as to move the piston toward the left, operating thelevers to release the clamping bands and permit the electrode to slidedownward.

In Fig. 8 is shown a modification of the invention in which aspring-loaded cylinder is operatively connected to a pair of decussatelypivoted levers which operate the clam-ping bands around the electrode.

In this embodiment of the invention the cylinder is indicated generallyat 92 and is provided at one end with a head 93 having a rod 94 formedintegrally thereon, or rigidly attached thereto, and provided with aneye 95 for pivotal connection by a pivot pin 96 to the upper end of oneof the decussately pivoted levers 97.

An inlet passage 98 is formed in the head 9.3 and come municates withthe water supply pipe 57 such as shown diagrammatically in Fig. 6. Anoutlet passage 99 in the head 93 communicates with the water dischargepipe 59 which is the same as shown diagrammatically in Fig. 6.

Thus cooling water may be continuously passed through the left end ofthe cylinder 92, on the left side of the piston 100 therein, from thewater supply pipe 57 to the water discharge pipe 59 and the same may becontrolled by the valve 60, as shovm in Fig. 6 andv above described, soas to become a trapped system upon which high pressure can be applied tomove the piston 100 toward the right, against the pressure of thecompression spring 101 which is located on the right side of the pistonbetween the same and the head 102 of the cylinder.

The piston rod 103 is located through a suitable stuifing box 104 in thehead 102 and provided at its end with an eye 105 for pivotal connection,as by the pin 106, with the upper end of the other decussately pivotedlever 97.

Cooling water may be continuously circulated through the cylinder on theright side of the piston to cool the spring 101 and adjacent parts ofthe cylinder and piston. For this purpose a cooling water inlet 107 anddischarge outlet 108 are formed in the head 102.

Each of the levers 97 may be hollow and may be water cooled in anyconventional manner. The intermediate portions of the levers 97 arecrossed and pivoted, as by the pivto pin 109. Bosses 18a are formed uponthe lower ends of the levers 97 for engagement in the sockets 16 of theclamping bands 11 which may be of the same construction as shown inFigs. l to 4, and the same reference numerals are applied thereto.

With this construction, as shown in Fig. 8, the compression spring 101normally urges the piston 100 to the left, as viewed in the drawings,pulling the upper ends of the decussately pivoted levers 97 toward eachother and correspondingly moving the lower ends of the levers towardeach other, so that the bosses 18o thereon engaging the sockets 16 ofthe clamping bands 11 hold the clamping bands tightly against theelectrode.

Cooling water is continuously passed through both sides of the cylinder,and when it is desired to release the clamping bands to permit theelectrode to slide downward in the furnace, the valve 60 in Fig. 6 isoperated to trap the water in the pipe 59 so as to cause the Waterpressure in the left side of the cylinder to urge the piston 100 towardthe right, against the pressure of the spring 101, moving the upper endsof the levers 97 apart and correspondingly moving the lower ends thereofaway from each other, so as to release the clamping bands 1l.

It should be understood that in the form of the invention shown in Fig.8, with the decussately pivoted levers, a compressible fluid-operatedcylinder may be substituted for the spring-loaded cylinder 92.

From the above it will be obvious that an automatic electrode clampingdevice is provided in which the clamping bands are operated by leversremotely controlled by an operating cylinder which may be either springloaded or compressible fluid-loaded.

The spring or compressible lluid is contained in a water-cooledenclosure together with the hydraulic cylinder. There is a continuouscircuit of Water cooling the interior of the cylinder on each side ofthe piston, and the water circuit on the side of the piston opposite tothe spring .or compressible fluid is so controlled as to become atrapped system upon which high pressure can be applied to operate thepiston against the pressure of the spring, or compressible uid, torelease the clamping bands.

It Will also be seen that the device includes a novel structure in theform ofthe duplex cylinder or fluidpressure accumulator for the purposeof applying high pressure to the Water trapped in the circuit supplyingthe spring-loaded or compressible fluid-loaded cylinder.

in the foregoing description, certain terms have been used for brevity,clearness and understanding, but no unnecessary limitations are to beimplied therefrom beyond the requirements of the prior art, because suchwords are used for descriptive purposes herein and are intended to bebroadly construed.

Moreover, the embodiments of the yimproved construction illustrated anddescribed herein are by way of example, and the scope of the presentinvention .is not limited to the exact details of construction.

Having now described the invention Lor discovery, the construction, theoperation, and use of preferred'embodiments thereof, and theadvantageous new and :useful results obtained thereby; the new anduseful construction, and reasonable kmechanical equivalents thereofobvious to those skilled in the art, are set forth in the appendedclaims.

I claim:

l. An electrode clamping device comprising clamping bands, a hydrauliccylinder having a piston therein :for operating the clamping bands,pressure means in the cylinder on one side of the piston for forcing theclamping bands into contact with the electrode, means providing acontinuous circuit of cooling Water within the cylinder on the otherside of the piston, and means for trapping the cooling Water in saidcircuit for applying presure against said other side of the piston toovercome said pressure means and release the clamping bands.

2. An electrode clamping device comprising clamping bands, a hydrauliccylinder having a piston therein for operating the clamping bands,pressure means in the cylinder on one side of the piston for forcing theclamping bands into contact with the electrode, means providing acontinuous circuit of cooling vater Within the cylinder on the otherside of the piston, means for trapping the cooling water in saidcircuit, and means for applying high pressure to the water trapped insaid circuit and against said other side of the piston to overcome saidpressure means and release the clamping bands.

3. An electrode clamping device comprising clamping bands, a hydrauliccylinder having a piston therein for operating the clamping bands,spring pressure means in the cylinder on one side of the piston forforcing the clamping bands into contact with the electrode, meansproviding a continuous circuit of cooling water Within the cylinder onthe other side of the piston, and means for trapping the cooling Waterin said circuit for applying pressure against said other side of thepiston to overcome said spring pressure means and release the clampingbands.

4. An electrode clamping device comprising clamping bands, a hydrauliccylinder having a piston therein, pivoted levers operatively connectingthe hydraulic cylinder and piston to the clamping bands, spring means inthe cylinder on one side of the piston for forcing the clamping bandsinto contact with the electrode, means for applying hydraulic pressureagainst the other side of the piston to overcome said spring means andrelease the clamping bands, and means for continuously circulatingcooling Water within said cylinder and around said spring means.

5. An electrode clamping device comprising clamping bands, a hydrauliccylinder having a piston therein, pivoted water-cooled leversoperatively connecting the hydraulic cylinder and piston to the clampingbands, spring means in the cylinder on one side of the piston forforcing the clamping bands into contact With the electrode, rmeans forapplying hydraulic pressure against the other side of the piston toovercome said spring means and release the clamping bands, and means forcontinuously circulating cooling Water Within said cylinder and aroundsaid spring means.

6. An electrode clamping device comprising clamping bands, a hydrauliccylinder having a piston therein, collaterally pivoted leversoperatively connecting the hydraulic cylinder and piston to the clampingbands, spring means in the cylinder on one side of the piston forforcing the clamping bands into-contact with the electrode, means forapplying hydraulic pressure against the other side of the piston toovercome said spring means and release the clamping bands, and means for`continuously circulating cooling Water within said cylinder and aroundSaid'spring means.

7. An electrode clamping device comprising clamping bands, a hydrauliccylinder having a piston therein, decussately pivoted levers operativelyconnecting the hydraulic cylinder and piston to the clamping bands,spring means in the cylinder on one side of the piston for forcing theclamping bands into contact with the electrode, means for applyinghydraulic pressure against the other side of the piston to overcome saidspring means and release the clamping bands, and means for continuouslycirculating cooling Water Within said cylinder and around said springmeans.

8. A11 electrode clamping device comprising clamping bands, a hydrauliccylinder having a piston therein for operating the clamping bands,spring means in the cylinder on one side of the piston for forcing theclamping bands into contact with the electrode, means providingcontinuous circuits of cooling water in the cylinder on each side of thepiston and around said spring means, and means for trapping the coolingWater in the circuit onthe opposite side of the piston from said springmeans for Aapplying pressure against said opposite side of the piston toovercome said spring means and release the clamping bands.

9. An electrode clamping device comprising clamping bands, a hydrauliccylinder having a piston therein for operating the clamping bands,spring means inthe cylinder on one side of the piston for forcing theclamping bands into contact With the electrode, means providingcontinuous circuits of cooling water in the cylinder on each side of thepiston and around said spring means, means lfor trapping the coolingWater in said circuit on the opposite side of the piston from saidspring means, and means for applying high pressure to the Water trappedin said circuit and against said opposite side of the piston to overcomesaid spring means and release the clamping bands.

10. An electrode clamping device comprising electrode clamping members,a cylinder for operating the clamping members, a spring-loaded piston inthe cylinder for urging the clamping members into clamped position,means for continuously water cooling the cylinder and the springtherein, and means for applying hydraulic pressure to the piston toovercome the spring and release the clamping members.

11. An electrode clamping device comprising electrode clamping members,a cylinder for operating the clamping members, a spring-loaded piston inthe cylinder for urgingthe clamping members into clamped position,

water supply and discharge pipes for circulating cooling water throughthe cylinder on the side of the piston opposite to the spring, anormally open valve in the discharge pipe, a duplex cylinder having apiston therein, a Water line located through the duplex cylinder on oneside of the piston therein and communicating with said water-supplypipe, a normally closed valve in said water line, an oil line connectedto the duplex cylinder on the other side of the piston therein, anormally closed valve in said oil line, and means for a simultaneouslyclosing said normally open valve and opening said normally closed valvefor trapping the cooling water in said water supply and discharge pipesand admitting oil pressure to said duplex cylinder to apply water underhigh pressure from said water line to said trapped water to overcome thespring pressure in said cylinder and release the clamping members.

12. An electrode clamping device comprising electrode clamping mem-bers,a cylinder for operating the clamping members, a spring-loaded piston inthe cylinder for urging the clamping members into clamped position,water supply and discharge pipes for circulating cooling water throughthe cylinder on the side of the piston opposite to the spring, anormally inoperative duplex cylinder, and means for simultaneouslytrapping the cooling water in said supply and discharge pipes andoperating the duplex cylinder to apply high pressure to the trappedwater to overcome the spring pressure and release the clamping members.

No references cited.

1. AN ELECTRODE CLAMPING DEVICE COMPRISING CLAMPING BANDS, A HYDRAULICCYLINDER HAVING A PISTON THEREIN FOR OPERATING THE CLAMPING BANDS,PRESSURE MEANS IN THE CYLINDER ON ONE SIDE OF THE PISTON FOR FORCING THECLAMPING BANDS INTO CONTACT WITH THE ELECTRODE, MEANS PROVIDING ACONTINUOUS CIRCUIT OF COOLING WATER WITHIN THE CYLINDER